连接数据

到目前为止，我们已经创建了隔离的无状态组件——这对 Storybook 来说很棒，但除非我们在应用中为它们提供一些数据，否则最终并没有什么用处。

本教程不侧重于构建应用程序的细节，因此我们不会在此深入探讨这些细节。但是，我们将花一点时间来了解将数据连接到已连接组件的常用模式。

已连接组件

我们当前编写的 TaskList 组件是“展示型”的，因为它不与其自身实现之外的任何事物进行交互。我们需要将其连接到数据提供程序以获取数据。

此示例使用 Redux Toolkit（用于开发应用程序以使用 Redux 存储数据的最有效工具集）为我们的应用程序构建一个简单的数据模型。但是，此处使用的模式同样适用于其他数据管理库，如 Apollo 和 MobX。

使用以下命令将必要的依赖项添加到你的项目中

yarn add @reduxjs/toolkit react-redux

首先，我们将在项目的根目录中创建一个名为 store.js 的文件，在其中构建一个简单的 Redux store，以响应更改任务状态的操作。

/* A simple redux store/actions/reducer implementation.
 * A true app would be more complex and separated into different files.
 */
import { configureStore, createSlice } from '@reduxjs/toolkit';

/*
 * The initial state of our store when the app loads.
 * Usually, you would fetch this from a server. Let's not worry about that now
 */
const defaultTasks = [
  { id: '1', title: 'Something', state: 'TASK_INBOX' },
  { id: '2', title: 'Something more', state: 'TASK_INBOX' },
  { id: '3', title: 'Something else', state: 'TASK_INBOX' },
  { id: '4', title: 'Something again', state: 'TASK_INBOX' },
];
const TaskBoxData = {
  tasks: defaultTasks,
  status: 'idle',
  error: null,
};

/*
 * The store is created here.
 * You can read more about Redux Toolkit's slices in the docs:
 * https://toolkit.redux.js.cn/api/createSlice
 */
const TasksSlice = createSlice({
  name: 'taskbox',
  initialState: TaskBoxData,
  reducers: {
    updateTaskState: (state, action) => {
      const { id, newTaskState } = action.payload;
      const task = state.tasks.findIndex((task) => task.id === id);
      if (task >= 0) {
        state.tasks[task].state = newTaskState;
      }
    },
  },
});

// The actions contained in the slice are exported for usage in our components
export const { updateTaskState } = TasksSlice.actions;

/*
 * Our app's store configuration goes here.
 * Read more about Redux's configureStore in the docs:
 * https://toolkit.redux.js.cn/api/configureStore
 */
const store = configureStore({
  reducer: {
    taskbox: TasksSlice.reducer,
  },
});

export default store;

然后，我们将更新 TaskList 组件以连接到 Redux store 并渲染我们感兴趣的任务

import { Task } from './Task';
import { FlatList, Text, View } from 'react-native';
import { LoadingRow } from './LoadingRow';
import { MaterialIcons } from '@expo/vector-icons';
import { styles } from './styles';
import { useDispatch, useSelector } from 'react-redux';
import { updateTaskState } from '../store';

export const TaskList = () => {
  // We're retrieving our state from the store
  const tasks = useSelector((state) => {
    const tasksInOrder = [
      ...state.taskbox.tasks.filter((t) => t.state === 'TASK_PINNED'),
      ...state.taskbox.tasks.filter((t) => t.state !== 'TASK_PINNED'),
    ];
    const filteredTasks = tasksInOrder.filter(
      (t) => t.state === 'TASK_INBOX' || t.state === 'TASK_PINNED'
    );
    return filteredTasks;
  });

  const { status } = useSelector((state) => state.taskbox);

  const dispatch = useDispatch();

  const pinTask = (value) => {
    // We're dispatching the Pinned event back to our store
    dispatch(updateTaskState({ id: value, newTaskState: 'TASK_PINNED' }));
  };

  const archiveTask = (value) => {
    // We're dispatching the Archive event back to our store
    dispatch(updateTaskState({ id: value, newTaskState: 'TASK_ARCHIVED' }));
  };

  if (status === "loading") {
    return (
      <View style={[styles.listItems, { justifyContent: "center" }]}>
        <LoadingRow />
        <LoadingRow />
        <LoadingRow />
        <LoadingRow />
        <LoadingRow />
        <LoadingRow />
      </View>
    );
  }

  if (tasks.length === 0) {
    return (
      <View style={styles.listItems}>
        <View style={styles.wrapperMessage}>
          <MaterialIcons name="check" size={64} color={"#2cc5d2"} />
          <Text style={styles.titleMessage}>You have no tasks</Text>
          <Text style={styles.subtitleMessage}>Sit back and relax</Text>
        </View>
      </View>
    );
  }

  return (
    <View style={styles.listItems}>
      <FlatList
        data={tasks}
        keyExtractor={(task) => task.id}
        renderItem={({ item }) => (
          <Task
            key={item.id}
            task={item}
            onPinTask={(task) => pinTask(task)}
            onArchiveTask={(task) => archiveTask(task)}
          />
        )}
      />
    </View>
  );
};

既然我们已经有一些实际数据从 Redux store 填充到我们的组件中，我们可以将其连接到我们的应用程序 App.jsx 并在那里渲染该组件。但是现在，让我们暂缓这样做，继续我们的组件驱动之旅。

使用装饰器提供上下文

我们的 Storybook stories 在此更改后停止工作，因为我们的 Tasklist 现在是一个已连接的组件，因为它依赖于 Redux store 来检索和更新我们的任务。

我们可以使用各种方法来解决此问题。不过，由于我们的应用程序非常简单，我们可以像在前一章中所做的那样，依赖一个装饰器，并在我们的 Storybook stories 中提供一个模拟的 store。

import { TaskList } from './TaskList';
import { Default as TaskStory } from './Task.stories';
import { View } from 'react-native';
import { Provider } from 'react-redux';

import { configureStore, createSlice } from '@reduxjs/toolkit';

// A super-simple mock of the state of the store
const MockedState = {
  tasks: [
    { ...TaskStory.args.task, id: '1', title: 'Task 1' },
    { ...TaskStory.args.task, id: '2', title: 'Task 2' },
    { ...TaskStory.args.task, id: '3', title: 'Task 3' },
    { ...TaskStory.args.task, id: '4', title: 'Task 4' },
    { ...TaskStory.args.task, id: '5', title: 'Task 5' },
    { ...TaskStory.args.task, id: '6', title: 'Task 6' },
  ],
  status: 'idle',
  error: null,
};

// A super-simple mock of a redux store
const Mockstore = ({ taskboxState, children }) => (
  <Provider
    store={configureStore({
      reducer: {
        taskbox: createSlice({
          name: 'taskbox',
          initialState: taskboxState,
          reducers: {
            updateTaskState: (state, action) => {
              const { id, newTaskState } = action.payload;
              const task = state.tasks.findIndex((task) => task.id === id);
              if (task >= 0) {
                state.tasks[task].state = newTaskState;
              }
            },
          },
        }).reducer,
      },
    })}
  >
    {children}
  </Provider>
);

export default {
  component: TaskList,
  title: 'TaskList',
  decorators: [
    (Story) => (
      <View style={{ padding: 42, flex: 1 }}>
        <Story />
      </View>
    ),
  ],
  argTypes: {
    onPinTask: { action: 'onPinTask' },
    onArchiveTask: { action: 'onArchiveTask' },
  },
};

export const Default = {
  decorators: [
    (story) => <Mockstore taskboxState={MockedState}>{story()}</Mockstore>,
  ],
  args: {
    // Shaping the stories through args composition.
    // The data was inherited from the Default story in Task.stories.js.
    tasks: [
      { ...TaskStory.args.task, id: '1', title: 'Task 1' },
      { ...TaskStory.args.task, id: '2', title: 'Task 2' },
      { ...TaskStory.args.task, id: '3', title: 'Task 3' },
      { ...TaskStory.args.task, id: '4', title: 'Task 4' },
      { ...TaskStory.args.task, id: '5', title: 'Task 5' },
      { ...TaskStory.args.task, id: '6', title: 'Task 6' },
    ],
  },
};

export const WithPinnedTasks = {
  decorators: [
    (story) => {
      const pinnedtasks = [
        ...MockedState.tasks.slice(0, 5),
        { id: '6', title: 'Task 6 (pinned)', state: 'TASK_PINNED' },
      ];

      return (
        <Mockstore
          taskboxState={{
            ...MockedState,
            tasks: pinnedtasks,
          }}
        >
          {story()}
        </Mockstore>
      );
    },
  ],
  args: {
    // Shaping the stories through args composition.
    // Inherited data coming from the Default story.
    tasks: [
      ...Default.args.tasks.slice(0, 5),
      { id: '6', title: 'Task 6 (pinned)', state: 'TASK_PINNED' },
    ],
  },
};

export const Loading = {
  decorators: [
    (story) => (
      <Mockstore
        taskboxState={{
          ...MockedState,
          status: 'loading',
        }}
      >
        {story()}
      </Mockstore>
    ),
  ],
  args: {
    tasks: [],
    loading: true,
  },
};

export const Empty = {
  decorators: [
    (story) => (
      <Mockstore
        taskboxState={{
          ...MockedState,
          tasks: [],
        }}
      >
        {story()}
      </Mockstore>
    ),
  ],
  args: {
    // Shaping the stories through args composition.
    // Inherited data coming from the Loading story.
    ...Loading.args,
    loading: false,
  },
};

成功！我们回到了起点，我们的 Storybook 现在可以工作了，并且我们能够看到如何将数据提供给已连接的组件。